This invention relates to a method of blasting a field.
In a particular aspect, this invention relates to a method of blasting a field using an expanded bore hole pattern.
The ammonium nitrate-fuel oil mixture generally known as ANFO is in very widespread use for blasting, especially in large scale operations where an extensive field is to be blasted for easy removal, such as in strip mining operations. The bore holes, into which the ANFO is loaded, must be drilled rather close together, generally 2 ft..times.2 ft. for each one inch of bore hole diameter, e.g. about 10-12 feet apart for 6 inch diameter holes in most structures, to provide satisfactory breakage of the geological formation where the blasting is conducted. A problem faced by ANFO users is water in the bore holes. It is a common experience that water collects in the holes before the drilling and loading of the holes can be completed. As a result, it is common practice to load a high explosive into the hole before adding the ANFO. The high explosive is selected to be unaffected by water and to be dense enough to sink in the water. However, high explosives are undesirable because they are more hazardous to handle and to transport than nitro-carbo-nitrates.